Kevin de Bruyne’s left foot had helped ease Manchester City’s passage into the Champions League quarter-finals with a glorious goal against Borussia Monchengladbach. Then he toed the party line. “We focus game by game,” he said. It is a cliched formula that has served them well. In their last 25 games, City have won 24; 15 with clean sheets, 19 by at least two goals. The <a href="https://www.thenationalnews.com/sport/football/manchester-city-s-glorious-run-ends-with-painful-defeat-to-manchester-united-1.1179705">defeat against Manchester United</a> apart, they have trailed for 22 minutes. It represents a startling turnaround. In September, City conceded five times in a match, the first time a Pep Guardiola side had ever done that. In December, the Catalan admitted: “I don’t like my team, the way we play.” They were level on points with 10th-place Wolves. Since then, they have won 96 per cent of their games. The prospect of ignominy has been replaced by the chance to make history. Two years ago, City did an unprecedented treble of the Premier League, the FA Cup and the League Cup. No English club has ever done the quadruple. One is determined not to talk about it. <a href="https://www.thenationalnews.com/sport/football/pep-guardiola-dismisses-manchester-city-s-quadruple-dreams-as-utopia-1.1184764">Guardiola rebuked Oleksandr Zinchenko</a> for sounding bullish on Tuesday when the Ukrainian said: "Everything is possible." The manager’s argument has been consistent. "When you say, 'Why don't you win the four titles?' It's impossible for that to happen," he said. That was in 2018, when City posted 100 points but went out of the FA Cup to League One Wigan and suffered the first of three consecutive Champions League quarter-final exits. “People two years ago were saying that we could win it,” said De Bruyne who, unlike Zinchenko, adhered to Guardiola’s school of thought. “The amount of games and the physical and mental ability you need to have as a player or as a squad is very high.” As City know more than most, knockout competitions mean one game, one decision, one error or one miss can end the chance of a clean sweep. Fabian Delph’s rash lunge reduced them to 10 men at Wigan in 2018. The <a href="https://www.thenationalnews.com/sport/football/spurs-survive-seven-goal-thriller-to-end-man-city-s-quadruple-quest-1.850472">2019 Champions League exit to Tottenham</a> included a Sergio Aguero penalty miss, a Fernando Llorente decider that brushed his arm before going in off his hip and an injury-time City 'winner' that was celebrated before being disallowed by VAR. In short, City need to be flawless on three fronts now. They only have margin for error is the Premier League. Sixteen points from nine games will make a third title in four years mathematically certain; nine should probably suffice. The League Cup is the next most attainable. Only Tottenham separate City from a fourth successive Wembley win in the competition but the temptation to assume the final is a formality should be ignored. Guardiola has a reputation as Jose Mourinho’s nemesis, but the Portuguese has nine wins in their meetings, two of them with Tottenham. The FA Cup takes City to Everton on Saturday, where Guardiola has lost 4-0, against Carlo Ancelotti, whose Real Madrid ended his Bayern Munich’s hopes of a treble in the 2014 Champions League semi-finals. The competition still includes Leicester, triumphant 5-2 against City this season, Chelsea, unbeaten under Thomas Tuchel, and United, with Ole Gunnar Solskjaer boasting a winning record against Guardiola. And yet there is no doubt the Champions League represents the hardest to win. Monchengladbach captain Lars Stindl called City “the best team in the world at the moment” but Guardiola would argue Bayern are the favourites. They proved last year they can beat Europe’s best. They have 18 victories in their last 19 Champions League games and an attack spearheaded by 39-goal Robert Lewandowski, as many as Raheem Sterling, Gabriel Jesus, Bernardo Silva, De Bruyne and Aguero have between them. Anyone who wants to secure the Champions League will have to beat Bayern or Paris Saint-Germain, if not both, and City’s ambitions were thwarted by Mauricio Pochettino two years ago. It is also worth noting that only seven clubs have won it as part of the most prestigious treble and Ajax, PSV Eindhoven and Celtic were in very different domestic leagues. It leaves United, Mourinho’s Inter Milan and two Bayern and Barcelona sides, one managed by Guardiola. He speaks from experience when he says how hard a quadruple is, so it would be a stunning achievement if City managed it.